I like the free version of HWMonitor from CPUID.com for such probing. Here are the results from one of my testbed xw6400 workstations with two of the fastest processors HP certified for it (E5345, SLAEJ sSpec code). And, 16GB of memory in the 4 slots as 4x4.... HP memory is all I use. I work off of this box, amongst others. The memory is used, off eBay, and now has become quite reasonable in price even for 4GB HP sticks.
I'll get you the Assembly P/N tomorrow for those.
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With W7Pro64 or W10Pro64AU that workstation still is excellent. There is a BIOS setting for fan speed but its default is down at the lowest value.
I have not seen fan speed go up with more memory on any recent builds on the xw6400, and make sure you are using the latest BIOS. I have seen bad thermisitors in the front on/off cable force the motherboard to detect danger and ramp up the fan speed, but that is a big ramp-up, and is fixed with a cable replacement, and it has not been related to amount of memory present. I used to think otherwise but have not seen that in practice for years now.
16GB of HP memory gets the job done that I need this workstation to do..... with breathing room to spare. My main point is that HP builds workstations that have a long life in them. I continue to be highly impressed with the xw6400 as long as it is running 2 x E5345 SLAEJ, and 8 or 16GB of HP RAM, and the Intel SATA Gen II SSDs I have posted about in 160GB or 300GB form. Then, there are the proper BIOS settings, and on. The information is all in here, which is quite handy.
